The present invention relates in general to a magnetic drum head system for selectively generating recorded voice information, or an automatic message announcement system, and more particularly to a magnetic drum unit for a voice generation or announcement system, which is used, for example, in a device for reproducing a warning sound or reproducing a voice. The system is used in vehicle, or vending machines.
In announcing systems such as automobile status monirots, vending machines, various terminal equipment, elevators, loudspeaker equipment and the like, it has been recently proposed that the employment of a magnetic drum system may lead to a useful result. In these uses the requirements are such that audio signals (analog signals) can be recorded and reproduced directly and that a plurality of messages can be accessed at random. A system is available satisfying these requirements by dividing a recording medium layer on the surface of a magnetic drum into a plurality of tracks and recording and reproducing information (messages) on each track by a magnetic head.
A magnetic drum/head system for the voice information is described in U.S. Pat. No. 4,376,961, assigned to the present assignee.
The present invention affords a magnetic drum mechanism which if formed and packaged into a cassette, which is releasably mounted to a magnetic head mechanism of a voice information system.
In a known magnetic drum system as is applied in various fields of art in which an information track or channel is searched while the magnetic drum is being rotated at a relatively high speed, the magnetic head approaches the selected track of the drum by way of the other unselected tracks with the magnetic head being in contact with the magnetic drum.
In the various fields to which the magnetic drum system is applied, it is necessary that the drum system be miniaturized, lightweight and be highly durable. In order to miniaturize a magnetic drum, it is necessary to decrease the circumferential speed or rim speed of the drum while a predetermined output level is obtained by pressing the magnetic head onto the surface of the magnetic drum since the lower rim speed results in a decrease of an output level. However, when the magnetic head is pressed with a stronger force than usual against the magnetic drum, it is likely that the magnetic head and drum are rapidly worn out due to an unnecessary frictional contact between the drum, rotating at a high speed, and the magnetic head. Further, such an undesirable frictional resistance increases wow/flutter, and consequently, the desired reproduction of the recorded information is not obtained.
In many cases, it is desired or necessary that recorded information i.e., the message, be changeable such that other information can be recorded and played back from the drum. In the conventional system, the system with the magnetic drum mounted therein is sealed, and therefore it is impossible or quite difficult to access to the magnetic drum after the drum is assembled into the system. A reason for this is to prevent foreign particles from adhering to the magnetic drum so as to avoid failure of desired reproduction of voice information and consequent decrease of reliability of the operation of the drum. Particularly when oil such as silicone oil is coated on the circumference of the magnetic drum so as to eliminate a frictional resistance between the magnetic head and the magnetic drum, it is necessary to seal or fully enclose the mechanism. Another reason for sealing the mechanism of the drum is to prevent a change of properties due to long-time exposure to ultraviolet light.
Accordingly, in order to modify and change the recorded information, a troublesome rewriting operation is required in the conventional system.